Redirected internet address

I have a small but irritating problem with IE (previously 9, but now 11) and Firefox. My wife likes to buy on-line from a site called slapwatch.com (guess what they sell!) with whom we have done business for quite some time. However, for the last few months, whenever I enter the address slapwatch.com, it gets substituted by slapwatches.com.au. If I click on this address, I get the message that the address cannot be found. I contacted Slapwatch by telephone and was advised that the address in question referred to an Australian subsidiary which had been closed down some months previously. Assuming that the redirect had been applied with good intentions (to benefit the subsidiary company and reduce postage costs for the consumer), can anyone please advise me how to remove it.

As an aside, with IE11 (which was installed by a techie after a nasty cyber attack left me with no option but to reformat the disk and reinstall software), I get a window every so often asking me to activate the program by telephoning, buying a new activation key, or quoting the one I already have. Is this kosher? The cyber attack I referred to was initiated when I bought some software called ErrorEnd and the email receipt asked me to install and validate it by telephoning a tech representative. I did this and all seemed to go well until my computer started behaving very strangely and I began receiving telephone calls saying that Microsoft had noted my problem (how, I do not know - the slow speed could not be handled by my WiFi connection!) and asked them to help me out, so since then I have been very chagey about allowing any outside party to take control of my PC. I expressed my concerns about the security of their delivery processes to the ErrorEnd management and to their credit, they immediately refunded the purchase price. There are still a few ethical suppliers around!

Do you know where the substitution is performed? Is it IE, or does it occur after you go to the slapwatch site? If it's IE it will be stored in the URL cache and you should be able to delete it by dragging down the history list in the Address Bar, and click on the Delete (red delete mark) that appears when hovering the mouse over the entry.

I don't have IE11, but I didn't think it needed activation. I'm sure someone else will confirm.

Thanks for confirming my suspicions regarding activation of IE11. I suspect it might be a phishing attempt (though I did read somewhere that Microsoft was introducing activation for Windows and IE because they were concerned about piracy. Anyway, I will ignore it for now, irritating though it is. With regard to the other issue, I have looked carefully at the connection process to see where the redirection comes from and I think that it is being done from the other end. After one enters a destination address, a tab is opened and the name of the site appears. In my case, a reference to slapwatch. com is displayed, but only for a second or two before being replaced by the redirected address.
Sorry to have taken up your valuable time unnecessarily, but after my recent experiences, I tend to view everything that is not rock standard as a potential threat!

Where do you enter the destination address? In the address bar of IE?
It may be worth checking the IP address for slapwatch to see where you are being sent. Enter these commands and post the result.
Start > Run > cmd
ping slapwatch.com

I get this responsePinging slapwatch.com [97.74.124.158] with 32 bytes of data:
Reply from 97.74.124.158: bytes=32 time=156ms TTL=43

I would not ignore the activation message, you have malware on your system and need to fix it now.